1. Field of the Invention
The present invention relates to a sheet length measuring device and an image forming apparatus.
2. Description of the Related Art
In the past, there has been known a technology for installing a sheet length measuring device (transfer target length measuring device) that measures a length of a sheet, such as a transfer paper, in an image forming apparatus, such as a copier or a printer (see, for example, Japanese Patent Application Laid-open No. 2010-241600).
In Japanese Patent Application Laid-open No. 2010-241600 or the like, disclosed is a technology that is intended to measure a length of a transfer target (sheet) with a high degree of accuracy even when a roller diameter of a carriage roller is changed by eccentricity, thermal expansion, or the like, and calculates a length of a transfer target based on a conveying distance and a rotation amount of a rotating body in a first measuring period and a conveying speed in a second measuring period.
In the above-disclosed technology of Japanese Patent Application Laid-open No. 2010-241600, an effect of being able to measure a length of a sheet with a high degree of accuracy even in the event of the occurrence of eccentricity, thermal expansion, or the like in a rotating body (carriage roller) can be expected, but the measurement of a sheet length is complicated, such as there being a need to measure a conveying distance of a sheet or the like several times.
Therefore, there is a need for a device capable of measuring a length of a sheet with a high degree of accuracy by a relatively simple and easy method even in the event of the occurrence of eccentricity, thermal expansion, or the like in a rotating body.